It has been a practice in the pultrusion of articles such as window spacers, for example, to prepare the article by passing reinforced strands or rovings through a resin bath with an appropriate fibrous, continuous strand mat surrounding the rovings. The mat and rovings as they pass through bath are impregnated with a resin, typically an unsaturated polyester. The resin rich mat and strands are then fed to a pultrusion die and are pulled through the die. The die is normally heated to provide a temperature sufficient to cause the resin to cure so that a solid article is removed from the exit end of the die. The process is convenient in preparing articles such as window and/or door framing members. A more complete description of the typical pultrusion process used to prepare each article is contained in European patent application No. 0 113 209.
While the aforementioned patent describes a process and articles of manufacture that are useful, there are some drawbacks to both. In preparing parts which have ribbing or sharp turns, it has been found that the mat used frequently does not fill the turns or ribs to the full depth of either. This leaves a portion of the part without the desired mat reinforcement. Further, the parts frequently do not possess surfaces that are acceptable in the aesthetic sense. It has also been found that the chemically bonded mats heretofore employed in the pultrusion processes hereinbefore discussed, frequently are inadequate in strength in narrow widths to withstand the pulling forces to which they are subjected without tearing during pultrusion.
Thus a need exists in the art for reinforcements for use in pultrusion processes that have satisfactory handling characteristics so that all portions of a pultruded part are reinforced on a substantially uniform basis. Pultruded articles having substantially uniform reinforcement throughout, and tensile properties in all direction that are adequate for the intended use are also needed. Finally, a need exists for pultruded products which have good surface appearance on all surfaces of the part. The present invention supplies these needs.